Discussions

Specifications

Balancing is usually left until project completion on the assumption that the system is installed as expected. Don't count on it. Adjustments are always needed. Performance always needs to be evaluated. But first start off with HVAC systems that deliver design CFM in the right place at the right time. But you knew that.

Effectiveness

Building HVAC just runs. Or does it? Correct balancing ensures air is delivered to where specified at the proper CFM levels. Trust but use balancing to verify.

Saving Energy

Start with an Energy Star evaluation using EPA's Portfolio Manager. Quickly learn the energy performance of a building compared to all similar buildings in the country, weather corrected. Always the best way to track building energy effectiveness.

Conserving Resources

Start with an examination of current air delivery to the space. Verify it is as designed and corrected for actual conditions. It isn't possible to conserve energy sources unless air handlers and rooftop units operate as expected.

Utility Bills

Leverage the builtin power of utility bills to track energy usage over time through Portfolio Manager. There is no such thing as effectively comparing energy usage from month to month, even using regression analysis. Rely on year to year comparisons to understand building energy performance.

Equipment Performance

Track energy performance, not by measuring motor energy, but by measuring air delivery. Do it over extended time periods to gain an understanding of system performance. Then tweak control parameters to reduce operating energy and associated costs.

Demand Management

Utilities charge for their fixed assets. When peak summer air conditioning loads hit, so do their peaker plants. Compensation for peak demand is to charge more aggressively in the summer. Peak demand charges, interestingly, often equal energy consumption charges. Cut back on energy as you like. But that one time the chiller starts during a given summer month will result in big demand charge. Set that peak demand one time, in May, and count on being hit with at least a high percentage of that peak demand charge in the subsequent summer months. Reducing demand charges is easy. You just need to know how.

Focus

Inspect control methods and algorithms for each specific air handler or rooftop unit. Ensure that embedded control methods deliver the expected air throughout the year. And verify air delivery by tracking it every few minutes. Use Ambient Building's performance tracking technology to recognize unusual usage. And rely on its alerts for prompt notification.

Non-stop

Air side controllers just work. But they can work in mysterious ways. Equipment operating specs are fixed but equipment operation drifts. Non-stop controllers need continuous assessment. Data-driven performance tracking is key to understanding individual air handler and rooftop unit performance. Let data work for you. Not you work for data.

Measuring

We don't. There are no known methods to end-measure HVAC impact on occupant health. There are only intermediate measurements like temperature and humidity. But these fail to address the non-tangible impact of HVAC on occupants.

Controls

Building automation systems (BAS) do one thing well: Manage independent controllers using computer based front-end technology to simplify controller parameter adjustment. What they don't do well is evaluate subtle influences on occupant comfort like dust and volatiles. Modern WiFi-connected devices are more suited to this work. Consider improving information feedback to improve occupant safety, health, and productivity.

Feedback

Do the obvious: Count reported sickness days. Count the number of children going to the school nurse. Count number of children not returning to school in the middle of the week because of environmental conditions. Then compare these numbers to HVAC and space environmental conditions. There's knowledge in these numbers.

Sufficient?

Outside air is the bogeyman of today's tightly sealed buildings. More is suppose to be better. But that depends on building location and exposure to other environmental influences. Just where is that "clean" outside air? Maybe it needs to be additionally cleaned up. Or maybe special air treatment can minimize the need for outside air. It all matters.

Cleanup

Good filtration helps. But it isn't sufficient. Traditional filtration picks up large dirt particles. And today's MERV filtration standards pick up even more of the small dust particles floating in the air. That's if they make their way to the filter. And that depends on individual room circulation and return air method used. So good filtration is a start but it's not sufficient.

Mitigation

These elements are so small that they float through even the best commercial filtration. The only way to attack them is through mitigation. You can't kill a virus (a protein) but you can deactivate it using ultraviolet light (264 um). And you can aggomulate them into larger particles, using negative ions, that can be captured in high-quality filtration or inactivated using ultraviolet light inside an air handler or rooftop unit.

Nuclei

These particles float easily is dry air. And less so in moist air. They can't be captured in filters, however, unless they float in the air stream on its way back to the circulation fan. Some will land on the walls and plastic objects with positive charges. They'll die after a few days or can be killed with the proper wipe. For the others, however, a combination of high filtration, negative ion treatment, and UV-C light works effectively

Winter

Few buildings are equipped with humidification equipment. Usually it's only found in medical facilities. Recent research better understands how humidity affects viruses and bacteria. We can do better, even if only incrementally. One way is to more carefully evaluate outside air quantities that dry out the indoor environment. Different filtration methods can help such as activated charcoal and gas removal products. Reducing outside air has always been the goal of effective energy management. But it's not that simple when considering viruses floating in air. Investigate humidity for your building from a health viewpoint and less as an energy conservation method. And balance these perspectives by considering the combinations of negative ion, UV-C, and improved filtration methods now available.

Summer

Humidity matters during warmer months. Dry air improves the learning environment. And, more recently, we've learned that overly moist air promotes the growth of viruses and bacteria in the space. This is where equipment air conditioning performance takes on additional importance. Discharge air temperatures signal air moisture levels. And the ability to achieve low discharge air temperatures is better understood when knowing compressor suction temperatures. The process continues. Variables are important.

Electronic

Modern buildings, over the past 30 years, are usually equipped with electronic controls. Actuators use small motors to position dampers and move valves. Communications between sensors and actuators happens through pre-programmed controllers dedicated to specific applications. It's all good. Except when it isn't. And that happens when a single contractor or vendor claims exclusive knowledge or access to controller algorithms or communications protocol. There are ways, today, to beat this type of monopoly.

Pneumatic

Older buildings are often a combination of pneumatic and electronic controllers. Pneumatic actuators drive dampers and valves handily. Are they obsolete? No. Should they be replaced? Mostly. But use the controls a building has and track results over time as part of a performance analysis. There may be life, yet, in pneumatic controls.

Delivery

Ductwork moves air throughout a building. Is it effective? Likely. But terminal devices are the great determiner of air effectiveness. So pump up supply duct air pressure to move the air into position. Let terminal units, like VAV boxes, make the final space delivery. And therein lies the problem. Are they calibrated appropriately? Does duct measurement match unit values? What is the minimum air circulation programmed for a given space? Is it sufficient for, say, moving air appropriately back to the air handler to capture dust particles. Is the discharge air temperature set to a lower than necessary value to compensate for a lack of cooling CFM in the space? Always questions. Use data to find the issues. Then use data to measure the results.

Return

Getting space air back to the supply unit is a given. Well, actually, it shouldn't be a given. Air handler return air will be pulled from somewhere in the building. But it may not be from the expected room. Wait, are you sure that delivered air is actually there? If you can't measure the room return air how do you know it is going back? Because the room must be pressurized, you say? But of course but where and how air returns is important to the success of ensuring ventilated supply air enters the breathability zone. Or does it rush across the ceiling and right back to the air handler? It's not enough to claim air delivery unless it is delivered to the right location within the room. Return air grilles can short circuit the air delivery process. Don't trust simple supply diffuser numbers. Know how space return affects supply and space breathability for occupants.

Sensors

Consider running a building without knowing space and key equipment temperatures. It won't happen. It can't happen because today's systems provide any number of temperature sensors. And maybe a humidity sensor here and there. Certainly at least one CO2 sensor is included - in the return air duct. Is this enough? No.

Space

Environmental space conditions are not simply temperature. Other variables should be considered like humidity, CO2, dust particulate count, volatile organic compounds, as well as ambient light and noise. Occupants, especially children and individuals with underlying health issues, react to far more than simple temperature measurements. It may not be possible to add humidity, but that doesn't mean other variables can't be mitigated.

Simple

Do a walk around. What's the temperature like? Wait that won't work - the building is too big. Besides what does this tell you that happened overnight? Look at the building automation system for tip offs to problems. What, you don't have time? Yeah, that's "simple".

Complex

Sit at the BAS console. Look through current air handler temperatures. Scan space temperatures looking for unusual situations. Back to the console. What was the discharge air temperature on unit five over the morning hours? But, of course, you don't know. It isn't easy to see it. And you've only got a few minutes in any case. So you spend time throughout the day, on and off, looking at current values. Almost a complete waste of your time.

Right

Use a data gathering tool to log and, cleverly, analyze temperatures and other variables from, maybe, hundreds of HVAC units. Don't bother with the BAS terminal. Instead look for the analysis tool to provide a summary list of issues. What? The BAS already provides alarms? That's no good. Alarms are not subtle. If they are included at all they are major disruptions. Were in-depth alarms included in the competitive bid contract? Almost never. What's needed is an in-depth analysis that looks for multiple variables that fit a pattern. It's the pattern that matters - not raw equipment alarms that no one wants to tweak properly. Unless, of course, they are paid handsomely.

Effective

It takes years to learn how a building operates. They have nuances built into the structure, HVAC, and controls. Modern BAS systems help minimize walking-around time. But that's not enough. Building managers need to know where they are needed most - and in advance of a major problem developing.

Actionable

Recently, Key Performance Indicators are the go-to method for understanding how HVAC equipment is or is not working. But KPIs can be overwhelming. Like, too many, while not producing enough time-saving suggestions. Actionable information, whether from KPIs or enhanced analysis, reduces the time involved in keeping a building running. Is this the way your building operates?

Mike Lavelle, P.E.